1. Field of the Invention
The present invention relates to a data reading device that reads out data from a non-volatile memory element in a semiconductor device.
2. Background Art
FIG. 7 is a circuit diagram of a data reading device that reads out data from a non-volatile memory element.
A data reading circuit 30 includes a PMOS transistor 31, a non-volatile memory element 32, a PMOS transistor 33, an NMOS transistor 34, and a latch circuit composed of inverter circuits 35 and 36.
The data reading circuit 30 reads out data from the non-volatile memory element 32 by performing an operation described below.
First, a signal Φ02 goes to a high level, causing the NMOS transistor 34 to turn on. The latch circuit composed of the inverter circuits 35 and 36 is reset, and an output terminal DOUT goes to a low level. Thereafter, the signal Φ02 goes to the low level and the NMOS transistor 34 turns off. Then, a signal Φ01 goes to the low level and the PMOS transistors 31 and 33 turn on.
In a depression state in which data has been written to the non-volatile memory element 32, the on-current of the non-volatile memory element 32 causes the latch circuit to be inverted to the high level, and the output terminal DOUT is retained at the high level.
On the other hand, in an enhancement state in which no data has been written to the non-volatile memory element 32, the output terminal DOUT is maintained at the low level (refer to, for example, Patent Document 1).
The potential state around the non-volatile memory element 32 remains the same at the time of reading data and at the time of writing data.
[Patent Document 1] Japanese Patent Application Laid-Open No. 2010-192039
In the data reading circuit 30, the potential state around the non-volatile memory element 32 remains the same at the time of reading data and at the time of writing data. Hence, there has been a danger that erroneous writing to the non-volatile memory element 32 occurs if a high voltage of static electricity or the like is applied to a supply terminal during a data reading operation.